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Re: Black specks on image.

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  • imontam
    Hi evrybody, Thanks for all the advice on the black specks. Concerning the rotation question, I did in fact mean that when I rotated the imager, the speck
    Message 1 of 10 , Dec 12, 2007
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      Hi evrybody,
      Thanks for all the advice on the black specks. Concerning
      the "rotation" question, I did in fact mean that when I rotated the
      imager, the speck pattern stayed put within the sensor and I could
      see the background moving around... indicating (not all that obvious)
      that the specks were part of the sensor. Leonard, your reply was
      particularly detailed and I printed it to include in my notes.
      Since I was planning another Mars imaging session tonight, I got
      busy putting some of the advice to use. I had already used
      the "oblique high intensity light" to actually see the specks on the
      cover glass, just before reading Leonard's message where he mentions
      the method. It works very well. The specks really stand out, they
      cant be missed. Pretty sure that was the source of the black
      blotches, I carefully rubbed the glass with a dry Q-Tip. After
      repeating the process 3 or 4 times and viewing the results with the
      imager back in the optical track, the dozens of specks have been
      reduced to one litte greyish speck in the bottom right-hand corner.
      So hopefully that is what I will see when I turn on my system tonight.
      While I am at it, here is some information regarding that matter
      of "signal loss" from the imager which generated quite a thread some
      time ago. I also had a bit of a problem with that. In the middle of
      operation, the imager would suddenly go dead. Since I use a remote
      viewing and control system (the telescope amd imager are outside and
      I control and view from my office inside, some 60 feet distant), I
      originally thought it was due to a quirky connection in the 4 USB
      cables that I have linked together. Or maybe the dampness would get
      to the last connection outside. When I went outside, just
      disconnecting (having shut down AMCAP before) and reconnecting the
      USB cables would bring back the image. But it was quite a hassle when
      it occured repeatedly. The other night, however, I discovered that
      just disconnecting and reconnecting the first USB cable in tne
      computer did the trick just as well. So it had nothing to do with
      outside conditions. I had a hunch all along that it was a software
      glitch, because the signal loss always occured after an operation
      such as "changing setup" in AMCAP, or "saving an image file",
      or "lauching the avi file capture"... it never came just out of the
      blue. So for me, disconnect and reconnect gets the signal back.

      Bye, Monti.
    • imontam
      Hi again, This is an update to the black speck problem. After having cleaned the cover glass of the Neximage, I had a 4 hour imaging session wednesday night,
      Message 2 of 10 , Dec 14, 2007
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        Hi again,
        This is an update to the "black speck" problem. After having
        cleaned the cover glass of the Neximage, I had a 4 hour imaging
        session wednesday night, observing Mars magnified 1000X (Neximage and
        2X barlow, with Celestron 8inch SC GPS) and making avi captures.
        Finally, the image was clean, completely free of any specks! Early in
        the session, there was considerable atmospheric turbulence, but this
        diminished gradually to give way later on to a nice calm and humidity
        free sky. I had started out making a few 500-frame captures, at
        1/10sec apperture and 5 frame/sec transfer rate. I eventually
        increased this to 1000, then 1500, and 2000. To close the session, I
        attempted a 2500-frame capture. It was successful. Since I want to
        avoid any telescope movements during a capture, Mars had to stay
        within the field of view. It drifted and wandered somewhat during the
        long capture, but not enough to interrupt it. I still have to process
        all these images, and am quite aware of the limitations of an 8 inch
        telescope with respect to resolution, however big the number of
        frames.
        By the way, while imaging Mars during december and perhaps
        beyond, I am also reading a very interesting book on the history of
        our relationship with and exploration of the planet. It is "A
        traveller's guide to Mars" by William K. Hartmann, 468p, 2003.
        Reading this simultaneously with the imaging makes the experience
        that much more fascinating.

        Bye, Monti.
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